Design of a transverse electric–pass/transverse magnetic–splitting three-guide directional coupler composed of two slot waveguides and one silicon wire

Abstract

A three-guide directional coupler composed of two slot waveguides and one silicon wire with a function of transverse electric (TE)-pass/ transverse magnetic (TM)-splitting is proposed and designed using a modified 3-D full-vectorial beam propagation method. In our design, quasi-TE modes fed in the middle silicon wire pass through without coupling, whereas quasi-TM modes fed in the same channel are evenly split into the outer slot waveguides. With properly chosen parameters, a TEpass/TM-splitting directional coupler with a length of 22.6 μm, including the straight coupling region and the S-bends, is achieved with the crosstalk of −31 and −35 dB for quasi-TE and quasi-TM modes, respectively. In addition, the tolerances to the structural parameters and operating wavelength are also investigated in detail. Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms Optical Engineering 094602-4 September 2012/Vol. 51(9) Wang, Xiao, and Sun: Design of a transverse electric-pass/transverse magnetic-splitting three-guide directional coupler composed : : : Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/terms